The present invention relates to an optical fiber splice sleeve and a method for applying the splice sleeve to recoat jointed optical fibers. More specifically, the present invention relates to an optical fiber splice sleeve with a disposable outer tube having a portion with diminished structural integrity, which portion facilitates removal of the outer tube.
Optical fiber lengths are connected or jointed together for many purposes including establishing long distance links. This type of connection is called a splice. For maximum performance, the splice should have the best possible alignment between the fiber cores, and retain that alignment. Splices can generally be categorized as mechanical splices or fusion splices, based on their principle of operation. Fusion splicing is an efficient technique for permanently jointing two fibers, and is known for its ability to achieve tight tolerances. However, very low signal loss and high mechanical strength are very difficult to achieve simultaneously in a fusion splice. Accordingly, it is necessary to protect the fusion fibers against environmental damage and to restore adequate strength at the point of the fusion splice. Often, a heat shrink tube is used to protect the splice point, since fusion spliced optical fibers show a significantly reduced tensile strength. However, more and more optical fiber is used in special applications like gyros and optical amplifiers where the fiber needs to be coiled up with a rather narrow diameter. For these applications it is not recommended to use heat shrink tubes, since they xe2x80x9cstiffenxe2x80x9d parts of the fiber.
Fiber recoating methods have been developed to provide splice protection and reinforcement without the use of heat shrink tubes. However, these prior fiber recoating methods have certain disadvantages. An apparatus for effecting one such recoating method is disclosed in U.S. Pat. No. 5,093,048, and is depicted in FIG. 1. A mold 18 includes spaced cylindrical passages 14 for securely clamping the optical fiber cable ends in place. The interior ends of the passages 14 open into a central enlarged cylindrical chamber 12 through which extend the spliced fiber optics 6 and 8. An inlet 16, formed in the body of the mold 18, allows the introduction of epoxy material into the central chamber 12. The epoxy surrounds the exposed fiber optics, including the fusion point 10. The mold is typically fabricated from a transparent plastic material, and a light-curable epoxy is used. The epoxy cures when exposed to light from a visible light source. Once the epoxy has cured, the recoated cable is removed from the mold.
The foregoing recoating technique for applying the splice sleeve has some significant disadvantages. First, a mold is required to accept the optical fibers and the epoxy, which seals the point of fusion of the optical fibers. Therefore, precisely toleranced molds must be used to facilitate recoating of the optical fibers. In addition, a visible light source is required to cure the epoxy for the splice sleeve. Accordingly, this conventional technique is cumbersome and expensive.
Another recoating technique is disclosed in Great Britain published application no. 2 136 349 A, and illustrated in FIGS. 2A and 2B. A fusion spice 24 is formed between optical fibers 20 having a cladding 22 of hardened resin. A semi-fluid resin 26 is applied to one surface of a length of tape 28. The tape 28 is folded around the fusion splice 24 to form a mold cavity 30. The volume of the mold cavity 30 is reduced by continuously squeezing the overlying end parts 36 of the tape 28 together by drawing them through a slot 34 of a die 38 to ensure that the mold cavity 30 is filled with resin 26. The resin is cured when it is exposed to UV light from a UV light source. After the resin 26 has cured, the tape 28 is peeled away.
This fiber recoating method also suffers from significant disadvantages. First, a die is required to continuously squeeze the tape to ensure that the mold cavity is filled with resin. In addition, a UV light source is required to cure the resin for the splice sleeve.
Therefore, a fiber recoating technique is needed which would reduce the number of necessary parts and the cost associated with the prior art fiber recoating techniques. The present invention was developed to accomplish these and other objectives.
In view of the foregoing, it is a principal object of the present invention to provide an improved optical fiber recoating sleeve and method for applying the same.
It is also an object of the present invention to provide an improved fiber recoating apparatus and technique, which eliminates the disadvantages associated with the mold, light source and die of the conventional recoating systems.
These and other objects are achieved by the present invention which, according to one aspect, provides an apparatus for recoating fused optical fibers which includes a tube and a fiber recoating material positioned inside of the tube, where the tube comprises a portion which facilitates separation and removal of the tube from the fiber recoating material.
According to another aspect of the present invention, an apparatus for recoating fused optical fibers is provided which includes a tube and a fiber recoating material positioned inside of the tube, where the tube is made from a non-stick material.
According to yet another aspect of the present invention, an apparatus for recoating fused optical fibers is provided which includes a tube and a fiber recoating material positioned inside of the tube, where an inner surface of the tube is coated with a non-stick material.
According to another aspect of the present invention, an apparatus for recoating fused optical fibers which includes a tube and a fiber recoating material positioned inside of the tube, where the tube is removable along a perforated portion.
According to yet another aspect of the present invention, an apparatus for recoating fused optical fibers is provided which includes a tube and a fiber recoating material positioned inside of the tube, where the tube comprises a molded imperfection which facilitates separation and removal of the tube from the fiber recoating material.
In yet another aspect of the present invention, an apparatus for recoating fused optical fibers is provided which includes a tube and a fiber recoating material positioned inside of the tube, where the tube comprises an element embedded in a portion of the tube which facilitates separation and removal of the tube from the fiber recoating material.
In another aspect of the present invention, a method of protecting and reinforcing fused optical fibers at a point of fusion is provided. The method includes providing a recoating sleeve comprising a hollow tube and recoating material disposed within the tube, positioning the recoating sleeve over the point of fusion, heating the recoating sleeve, and removing the tube to expose the recoating material.
These and other objects and features of the present invention will be apparent upon consideration of the following detailed description of preferred embodiments thereof, presented in connection with the following drawings in which like reference numerals identify like elements throughout.